Package javax.xml.validation Description

This package provides an API for validation of XML documents. Validation is the process of verifying
that an XML document is an instance of a specified XML schema. An XML schema defines the
content model (also called a grammar or vocabulary) that its instance documents
will represent.

There are a number of popular technologies available for creating an XML schema. Some of the most
popular include:

Document Type Definition (DTD) - XML's built-in schema language.

W3C XML Schema (WXS) - an object-oriented XML schema
language. WXS also provides a type system for constraining the character data of an XML document.
WXS is maintained by the World Wide Web Consortium (W3C) and is a W3C
Recommendation (that is, a ratified W3C standard specification).

Schematron - a rules-based XML schema
language. Whereas DTD, WXS, and RNG are designed to express the structure of a content model,
Schematron is designed to enforce individual rules that are difficult or impossible to express
with other schema languages. Schematron is intended to supplement a schema written in
structural schema language such as the aforementioned. Schematron is in the process
of becoming an ISO standard.

Previous versions of JAXP supported validation as a feature of an XML parser, represented by
either a SAXParser or DocumentBuilder instance.

The JAXP validation API decouples the validation of an instance document from the parsing of an
XML document. This is advantageous for several reasons, some of which are:

Support for additional schema langauges. As of JDK 1.5, the two most
popular JAXP parser implementations, Crimson and Xerces, only support a subset of the available
XML schema languages. The Validation API provides a standard mechanism through which applications
may take of advantage of specialization validation libraries which support additional schema
languages.

Easy runtime coupling of an XML instance and schema. Specifying the location
of a schema to use for validation with JAXP parsers can be confusing. The Validation API makes this
process simple (see example below).

Usage example. The following example demonstrates validating
an XML document with the Validation API (for readability, some exception handling is not shown):

The JAXP parsing API has been integrated with the Validation API. Applications may create a Schema with the validation API
and associate it with a DocumentBuilderFactory or a SAXParserFactory instance
by using the DocumentBuilderFactory.setSchema(Schema) and SAXParserFactory.setSchema(Schema)
methods. You should not both set a schema and call setValidating(true) on a parser factory. The former technique
will cause parsers to use the new validation API; the latter will cause parsers to use their own internal validation
facilities. Turning on both of these options simultaneously will cause either redundant behavior or error conditions.

Submit a bug or featureFor further API reference and developer documentation, see Java SE Documentation. That documentation contains more detailed, developer-targeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.